package sx.lambda.voxel.world.generation;

import java.util.Random;

/*
 * A speed-improved simplex noise algorithm for 2D, 3D and 4D in Java.
 *
 * Based on example code by Stefan Gustavson (stegu@itn.liu.se).
 * Optimisations by Peter Eastman (peastman@drizzle.stanford.edu).
 * Better rank ordering method by Stefan Gustavson in 2012.
 *
 * This could be speeded up even further, but it's useful as it is.
 *
 * Version 2012-03-09
 *
 * This code was placed in the public domain by its original author,
 * Stefan Gustavson. You may use it as you see fit, but
 * attribution is appreciated.
 *
 */

class SimplexNoise_octave {  // Simplex noise in 2D, 3D and 4D

    private static int RANDOMSEED = 0;
    private static int NUMBEROFSWAPS = 400;

    private static final Grad grad3[] = {new Grad(1, 1, 0), new Grad(-1, 1, 0), new Grad(1, -1, 0), new Grad(-1, -1, 0),
            new Grad(1, 0, 1), new Grad(-1, 0, 1), new Grad(1, 0, -1), new Grad(-1, 0, -1),
            new Grad(0, 1, 1), new Grad(0, -1, 1), new Grad(0, 1, -1), new Grad(0, -1, -1)};

    private static final Grad grad4[] = {new Grad(0, 1, 1, 1), new Grad(0, 1, 1, -1), new Grad(0, 1, -1, 1), new Grad(0, 1, -1, -1),
            new Grad(0, -1, 1, 1), new Grad(0, -1, 1, -1), new Grad(0, -1, -1, 1), new Grad(0, -1, -1, -1),
            new Grad(1, 0, 1, 1), new Grad(1, 0, 1, -1), new Grad(1, 0, -1, 1), new Grad(1, 0, -1, -1),
            new Grad(-1, 0, 1, 1), new Grad(-1, 0, 1, -1), new Grad(-1, 0, -1, 1), new Grad(-1, 0, -1, -1),
            new Grad(1, 1, 0, 1), new Grad(1, 1, 0, -1), new Grad(1, -1, 0, 1), new Grad(1, -1, 0, -1),
            new Grad(-1, 1, 0, 1), new Grad(-1, 1, 0, -1), new Grad(-1, -1, 0, 1), new Grad(-1, -1, 0, -1),
            new Grad(1, 1, 1, 0), new Grad(1, 1, -1, 0), new Grad(1, -1, 1, 0), new Grad(1, -1, -1, 0),
            new Grad(-1, 1, 1, 0), new Grad(-1, 1, -1, 0), new Grad(-1, -1, 1, 0), new Grad(-1, -1, -1, 0)};

    private static final short p_supply[] = {151, 160, 137, 91, 90, 15, //this contains all the numbers between 0 and 255, these are put in a random order depending upon the seed
            131, 13, 201, 95, 96, 53, 194, 233, 7, 225, 140, 36, 103, 30, 69, 142, 8, 99, 37, 240, 21, 10, 23,
            190, 6, 148, 247, 120, 234, 75, 0, 26, 197, 62, 94, 252, 219, 203, 117, 35, 11, 32, 57, 177, 33,
            88, 237, 149, 56, 87, 174, 20, 125, 136, 171, 168, 68, 175, 74, 165, 71, 134, 139, 48, 27, 166,
            77, 146, 158, 231, 83, 111, 229, 122, 60, 211, 133, 230, 220, 105, 92, 41, 55, 46, 245, 40, 244,
            102, 143, 54, 65, 25, 63, 161, 1, 216, 80, 73, 209, 76, 132, 187, 208, 89, 18, 169, 200, 196,
            135, 130, 116, 188, 159, 86, 164, 100, 109, 198, 173, 186, 3, 64, 52, 217, 226, 250, 124, 123,
            5, 202, 38, 147, 118, 126, 255, 82, 85, 212, 207, 206, 59, 227, 47, 16, 58, 17, 182, 189, 28, 42,
            223, 183, 170, 213, 119, 248, 152, 2, 44, 154, 163, 70, 221, 153, 101, 155, 167, 43, 172, 9,
            129, 22, 39, 253, 19, 98, 108, 110, 79, 113, 224, 232, 178, 185, 112, 104, 218, 246, 97, 228,
            251, 34, 242, 193, 238, 210, 144, 12, 191, 179, 162, 241, 81, 51, 145, 235, 249, 14, 239, 107,
            49, 192, 214, 31, 181, 199, 106, 157, 184, 84, 204, 176, 115, 121, 50, 45, 127, 4, 150, 254,
            138, 236, 205, 93, 222, 114, 67, 29, 24, 72, 243, 141, 128, 195, 78, 66, 215, 61, 156, 180};

    private short p[] = new short[p_supply.length];

    // To remove the need for index wrapping, double the permutation table length
    private final short perm[] = new short[512];
    private final short permMod12[] = new short[512];

    public SimplexNoise_octave(int seed) {
        p = p_supply.clone();

        if (seed == RANDOMSEED) {
            Random rand = new Random();
            seed = rand.nextInt();
        }

        //the random for the swaps
        Random rand = new Random(seed);

        //the seed determines the swaps that occur between the default order and the order we're actually going to use
        for (int i = 0; i < NUMBEROFSWAPS; i++) {
            int swapFrom = rand.nextInt(p.length);
            int swapTo = rand.nextInt(p.length);

            short temp = p[swapFrom];
            p[swapFrom] = p[swapTo];
            p[swapTo] = temp;
        }


        for (int i = 0; i < 512; i++) {
            perm[i] = p[i & 255];
            permMod12[i] = (short) (perm[i] % 12);
        }
    }

    // Skewing and unskewing factors for 2, 3, and 4 dimensions
    private static final double F2 = 0.5 * (Math.sqrt(3.0) - 1.0);
    private static final double G2 = (3.0 - Math.sqrt(3.0)) / 6.0;
    private static final double F3 = 1.0 / 3.0;
    private static final double G3 = 1.0 / 6.0;
    private static final double F4 = (Math.sqrt(5.0) - 1.0) / 4.0;
    private static final double G4 = (5.0 - Math.sqrt(5.0)) / 20.0;

    // This method is a *lot* faster than using (int)Math.floor(x)
    private static int fastfloor(double x) {
        int xi = (int) x;
        return x < xi ? xi - 1 : xi;
    }

    private static double dot(Grad g, double x, double y) {
        return g.x * x + g.y * y;
    }

    private static double dot(Grad g, double x, double y, double z) {
        return g.x * x + g.y * y + g.z * z;
    }

    private static double dot(Grad g, double x, double y, double z, double w) {
        return g.x * x + g.y * y + g.z * z + g.w * w;
    }


    // 2D simplex noise
    public double noise(double xin, double yin) {
        double n0, n1, n2; // Noise contributions from the three corners
        // Skew the input space to determine which simplex cell we're in
        double s = (xin + yin) * F2; // Hairy factor for 2D
        int i = fastfloor(xin + s);
        int j = fastfloor(yin + s);
        double t = (i + j) * G2;
        double X0 = i - t; // Unskew the cell origin back to (x,y) space
        double Y0 = j - t;
        double x0 = xin - X0; // The x,y distances from the cell origin
        double y0 = yin - Y0;
        // For the 2D case, the simplex shape is an equilateral triangle.
        // Determine which simplex we are in.
        int i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
        if (x0 > y0) {
            i1 = 1;
            j1 = 0;
        } // lower triangle, XY order: (0,0)->(1,0)->(1,1)
        else {
            i1 = 0;
            j1 = 1;
        }      // upper triangle, YX order: (0,0)->(0,1)->(1,1)
        // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
        // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
        // c = (3-sqrt(3))/6
        double x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
        double y1 = y0 - j1 + G2;
        double x2 = x0 - 1.0 + 2.0 * G2; // Offsets for last corner in (x,y) unskewed coords
        double y2 = y0 - 1.0 + 2.0 * G2;
        // Work out the hashed gradient indices of the three simplex corners
        int ii = i & 255;
        int jj = j & 255;
        int gi0 = permMod12[ii + perm[jj]];
        int gi1 = permMod12[ii + i1 + perm[jj + j1]];
        int gi2 = permMod12[ii + 1 + perm[jj + 1]];
        // Calculate the contribution from the three corners
        double t0 = 0.5 - x0 * x0 - y0 * y0;
        if (t0 < 0) n0 = 0.0;
        else {
            t0 *= t0;
            n0 = t0 * t0 * dot(grad3[gi0], x0, y0);  // (x,y) of grad3 used for 2D gradient
        }
        double t1 = 0.5 - x1 * x1 - y1 * y1;
        if (t1 < 0) n1 = 0.0;
        else {
            t1 *= t1;
            n1 = t1 * t1 * dot(grad3[gi1], x1, y1);
        }
        double t2 = 0.5 - x2 * x2 - y2 * y2;
        if (t2 < 0) n2 = 0.0;
        else {
            t2 *= t2;
            n2 = t2 * t2 * dot(grad3[gi2], x2, y2);
        }
        // Add contributions from each corner to get the final noise value.
        // The result is scaled to return values in the interval [-1,1].
        return 70.0 * (n0 + n1 + n2);
    }


    // 3D simplex noise
    public double noise(double xin, double yin, double zin) {
        double n0, n1, n2, n3; // Noise contributions from the four corners
        // Skew the input space to determine which simplex cell we're in
        double s = (xin + yin + zin) * F3; // Very nice and simple skew factor for 3D
        int i = fastfloor(xin + s);
        int j = fastfloor(yin + s);
        int k = fastfloor(zin + s);
        double t = (i + j + k) * G3;
        double X0 = i - t; // Unskew the cell origin back to (x,y,z) space
        double Y0 = j - t;
        double Z0 = k - t;
        double x0 = xin - X0; // The x,y,z distances from the cell origin
        double y0 = yin - Y0;
        double z0 = zin - Z0;
        // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
        // Determine which simplex we are in.
        int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
        int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords
        if (x0 >= y0) {
            if (y0 >= z0) {
                i1 = 1;
                j1 = 0;
                k1 = 0;
                i2 = 1;
                j2 = 1;
                k2 = 0;
            } // X Y Z order
            else if (x0 >= z0) {
                i1 = 1;
                j1 = 0;
                k1 = 0;
                i2 = 1;
                j2 = 0;
                k2 = 1;
            } // X Z Y order
            else {
                i1 = 0;
                j1 = 0;
                k1 = 1;
                i2 = 1;
                j2 = 0;
                k2 = 1;
            } // Z X Y order
        } else { // x0<y0
            if (y0 < z0) {
                i1 = 0;
                j1 = 0;
                k1 = 1;
                i2 = 0;
                j2 = 1;
                k2 = 1;
            } // Z Y X order
            else if (x0 < z0) {
                i1 = 0;
                j1 = 1;
                k1 = 0;
                i2 = 0;
                j2 = 1;
                k2 = 1;
            } // Y Z X order
            else {
                i1 = 0;
                j1 = 1;
                k1 = 0;
                i2 = 1;
                j2 = 1;
                k2 = 0;
            } // Y X Z order
        }
        // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
        // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
        // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
        // c = 1/6.
        double x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
        double y1 = y0 - j1 + G3;
        double z1 = z0 - k1 + G3;
        double x2 = x0 - i2 + 2.0 * G3; // Offsets for third corner in (x,y,z) coords
        double y2 = y0 - j2 + 2.0 * G3;
        double z2 = z0 - k2 + 2.0 * G3;
        double x3 = x0 - 1.0 + 3.0 * G3; // Offsets for last corner in (x,y,z) coords
        double y3 = y0 - 1.0 + 3.0 * G3;
        double z3 = z0 - 1.0 + 3.0 * G3;
        // Work out the hashed gradient indices of the four simplex corners
        int ii = i & 255;
        int jj = j & 255;
        int kk = k & 255;
        int gi0 = permMod12[ii + perm[jj + perm[kk]]];
        int gi1 = permMod12[ii + i1 + perm[jj + j1 + perm[kk + k1]]];
        int gi2 = permMod12[ii + i2 + perm[jj + j2 + perm[kk + k2]]];
        int gi3 = permMod12[ii + 1 + perm[jj + 1 + perm[kk + 1]]];
        // Calculate the contribution from the four corners
        double t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;
        if (t0 < 0) n0 = 0.0;
        else {
            t0 *= t0;
            n0 = t0 * t0 * dot(grad3[gi0], x0, y0, z0);
        }
        double t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1;
        if (t1 < 0) n1 = 0.0;
        else {
            t1 *= t1;
            n1 = t1 * t1 * dot(grad3[gi1], x1, y1, z1);
        }
        double t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2;
        if (t2 < 0) n2 = 0.0;
        else {
            t2 *= t2;
            n2 = t2 * t2 * dot(grad3[gi2], x2, y2, z2);
        }
        double t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3;
        if (t3 < 0) n3 = 0.0;
        else {
            t3 *= t3;
            n3 = t3 * t3 * dot(grad3[gi3], x3, y3, z3);
        }
        // Add contributions from each corner to get the final noise value.
        // The result is scaled to stay just inside [-1,1]
        return 32.0 * (n0 + n1 + n2 + n3);
    }


    // 4D simplex noise, better simplex rank ordering method 2012-03-09
    public double noise(double x, double y, double z, double w) {

        double n0, n1, n2, n3, n4; // Noise contributions from the five corners
        // Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in
        double s = (x + y + z + w) * F4; // Factor for 4D skewing
        int i = fastfloor(x + s);
        int j = fastfloor(y + s);
        int k = fastfloor(z + s);
        int l = fastfloor(w + s);
        double t = (i + j + k + l) * G4; // Factor for 4D unskewing
        double X0 = i - t; // Unskew the cell origin back to (x,y,z,w) space
        double Y0 = j - t;
        double Z0 = k - t;
        double W0 = l - t;
        double x0 = x - X0;  // The x,y,z,w distances from the cell origin
        double y0 = y - Y0;
        double z0 = z - Z0;
        double w0 = w - W0;
        // For the 4D case, the simplex is a 4D shape I won't even try to describe.
        // To find out which of the 24 possible simplices we're in, we need to
        // determine the magnitude ordering of x0, y0, z0 and w0.
        // Six pair-wise comparisons are performed between each possible pair
        // of the four coordinates, and the results are used to rank the numbers.
        int rankx = 0;
        int ranky = 0;
        int rankz = 0;
        int rankw = 0;
        if (x0 > y0) rankx++;
        else ranky++;
        if (x0 > z0) rankx++;
        else rankz++;
        if (x0 > w0) rankx++;
        else rankw++;
        if (y0 > z0) ranky++;
        else rankz++;
        if (y0 > w0) ranky++;
        else rankw++;
        if (z0 > w0) rankz++;
        else rankw++;
        int i1, j1, k1, l1; // The integer offsets for the second simplex corner
        int i2, j2, k2, l2; // The integer offsets for the third simplex corner
        int i3, j3, k3, l3; // The integer offsets for the fourth simplex corner
        // simplex[c] is a 4-vector with the numbers 0, 1, 2 and 3 in some order.
        // Many values of c will never occur, since e.g. x>y>z>w makes x<z, y<w and x<w
        // impossible. Only the 24 indices which have non-zero entries make any sense.
        // We use a thresholding to set the coordinates in turn from the largest magnitude.
        // Rank 3 denotes the largest coordinate.
        i1 = rankx >= 3 ? 1 : 0;
        j1 = ranky >= 3 ? 1 : 0;
        k1 = rankz >= 3 ? 1 : 0;
        l1 = rankw >= 3 ? 1 : 0;
        // Rank 2 denotes the second largest coordinate.
        i2 = rankx >= 2 ? 1 : 0;
        j2 = ranky >= 2 ? 1 : 0;
        k2 = rankz >= 2 ? 1 : 0;
        l2 = rankw >= 2 ? 1 : 0;
        // Rank 1 denotes the second smallest coordinate.
        i3 = rankx >= 1 ? 1 : 0;
        j3 = ranky >= 1 ? 1 : 0;
        k3 = rankz >= 1 ? 1 : 0;
        l3 = rankw >= 1 ? 1 : 0;
        // The fifth corner has all coordinate offsets = 1, so no need to compute that.
        double x1 = x0 - i1 + G4; // Offsets for second corner in (x,y,z,w) coords
        double y1 = y0 - j1 + G4;
        double z1 = z0 - k1 + G4;
        double w1 = w0 - l1 + G4;
        double x2 = x0 - i2 + 2.0 * G4; // Offsets for third corner in (x,y,z,w) coords
        double y2 = y0 - j2 + 2.0 * G4;
        double z2 = z0 - k2 + 2.0 * G4;
        double w2 = w0 - l2 + 2.0 * G4;
        double x3 = x0 - i3 + 3.0 * G4; // Offsets for fourth corner in (x,y,z,w) coords
        double y3 = y0 - j3 + 3.0 * G4;
        double z3 = z0 - k3 + 3.0 * G4;
        double w3 = w0 - l3 + 3.0 * G4;
        double x4 = x0 - 1.0 + 4.0 * G4; // Offsets for last corner in (x,y,z,w) coords
        double y4 = y0 - 1.0 + 4.0 * G4;
        double z4 = z0 - 1.0 + 4.0 * G4;
        double w4 = w0 - 1.0 + 4.0 * G4;
        // Work out the hashed gradient indices of the five simplex corners
        int ii = i & 255;
        int jj = j & 255;
        int kk = k & 255;
        int ll = l & 255;
        int gi0 = perm[ii + perm[jj + perm[kk + perm[ll]]]] % 32;
        int gi1 = perm[ii + i1 + perm[jj + j1 + perm[kk + k1 + perm[ll + l1]]]] % 32;
        int gi2 = perm[ii + i2 + perm[jj + j2 + perm[kk + k2 + perm[ll + l2]]]] % 32;
        int gi3 = perm[ii + i3 + perm[jj + j3 + perm[kk + k3 + perm[ll + l3]]]] % 32;
        int gi4 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1 + perm[ll + 1]]]] % 32;
        // Calculate the contribution from the five corners
        double t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0 - w0 * w0;
        if (t0 < 0) n0 = 0.0;
        else {
            t0 *= t0;
            n0 = t0 * t0 * dot(grad4[gi0], x0, y0, z0, w0);
        }
        double t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1 - w1 * w1;
        if (t1 < 0) n1 = 0.0;
        else {
            t1 *= t1;
            n1 = t1 * t1 * dot(grad4[gi1], x1, y1, z1, w1);
        }
        double t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2 - w2 * w2;
        if (t2 < 0) n2 = 0.0;
        else {
            t2 *= t2;
            n2 = t2 * t2 * dot(grad4[gi2], x2, y2, z2, w2);
        }
        double t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3 - w3 * w3;
        if (t3 < 0) n3 = 0.0;
        else {
            t3 *= t3;
            n3 = t3 * t3 * dot(grad4[gi3], x3, y3, z3, w3);
        }
        double t4 = 0.6 - x4 * x4 - y4 * y4 - z4 * z4 - w4 * w4;
        if (t4 < 0) n4 = 0.0;
        else {
            t4 *= t4;
            n4 = t4 * t4 * dot(grad4[gi4], x4, y4, z4, w4);
        }
        // Sum up and scale the result to cover the range [-1,1]
        return 27.0 * (n0 + n1 + n2 + n3 + n4);
    }

    // Inner class to speed upp gradient computations
    // (array access is a lot slower than member access)
    private static class Grad {
        double x, y, z, w;

        Grad(double x, double y, double z) {
            this.x = x;
            this.y = y;
            this.z = z;
        }

        Grad(double x, double y, double z, double w) {
            this.x = x;
            this.y = y;
            this.z = z;
            this.w = w;
        }
    }

}